Autopin machine

ABSTRACT

An apparatus and supply strip is disclosed for inserting terminal pins into an apertured workpiece. The apparatus includes reciprocating feeding means for sequentially advancing a supply strip of integrally connected preformed terminal pins toward the workpiece; shearing means for severing the leading one of said pins from the remainder of the supply strip; and driving means for inserting the severed lead one of said pins into the workpiece. The feeding means comprises grasping means operable only when the feeding means is moving in a first direction toward the workpiece to grasp the supply strip at the juncture of adjacent integrally connected preformed terminal pins.

This is a division, of application Ser. No. 773,274, filed Mar. 1, 1977,now abandoned.

FIELD OF THE INVENTION

This invention relates to an apparatus and supply strip for insertingelements such as electrical metal pins into an apertured workpiece suchas a printed circuitboard and more particularly relates to such anapparatus which operates from a continuous supply strip of integrallyconnected preformed terminal pins which when inserted in the workpiecewill leave exposed a pointed end portion.

BACKGROUND OF THE INVENTION

In the fabrication of many electrical products it is frequentlynecessary to establish a plurality of upstanding terminal pins on asubstrate. For example, on printed circuitboards, it is necessary toestablish terminal points to which external wiring can be secured.Various types of apparatus are known which operate from a continuoussupply strip to intermittently feed, sever and drive terminal pins intoa workpiece. However, all such known prior art apparatus and terminalpins inserted thereby suffer from the disadvantage that the terminalpins formed and inserted in the substrate terminate in end portionswhich have the same planar cross-sectional area as the supply stock fromwhich the terminal pins were formed.

Such blunt end portions of the terminal pins formed and inserted byapparatus of the prior art are particularly undesirable especially inthe environment in which a wire wrap operation is to be applied forelectrically connecting an external wire to the terminal pin. In fact,many OEM manufacturers who have to employ wire wrapping techniques toelectrically connect to printed circuitboards will refuse to acceptterminal pins in such boards where the terminals terminate in blunt endportions of the same planar cross-section as the pin itself. Apparently,the blunt nature of the terminal pins make it difficult to center thewire wrapping operation which is to take place for establishingelectrical connection to the printed circuits.

Another problem associated with the prior art apparatus for forming andinserting terminal pins in printed circuitboards, and somewhat relatedto the fact that the end portions of the inserted pins are of the sameplanar cross-section as the remainder of the pins, is the fact thatduring the shearing operation necessary to form the individual pins, anundesirable burr remains on the sheared pins. The thicker thecross-section of the supply stock, the more difficult it is to effect ashearing operation and the more pronounced is the undesirable burr whichresults.

SUMMARY OF THE INVENTION

The instant invention provides an apparatus and supply strip forinserting terminals into a substrate or workpiece such as a printedcircuitboard but which eliminates the aforedescribed problems inherentin the prior art machines and methods. More particularly, the novelsupply strip of the instant invention comprises a plurality ofintegrally connected preformed terminal pins each of which terminate inpointed end portions, whereby integrally connected against pointed endportions of adjacent pins form notch regions in the supply strip whichnotched regions are advantageously employed in the novel apparatushereof to sever and insert terminal pins in a workpiece such as aprinted circuitboard in such a fashion that the pointed end portions ofeach terminal pin end up being exposed to facilitate connection thereto.

In one embodiment of the novel supply strip hereof, the cross-section ofthe preformed integrally connected pins is rectangular in configurationwhereby the pointed end portions are prismatic in nature. In suchembodiment, the maximum chordal dimension from opposing corners of therectangular cross-section of the pin is greater than the diameter of theapertures into which the pins are inserted whereby a tight press fit ispossible.

In another embodiment of the invention, the terminal pins are ofcircular cross-section whereby the pointed end portions are of generallyfrustoconical configuration. In such an embodiment, a region of thelength of each pin is enlarged as by a swaging operation so as to make apress-fit possible even though the normal cross-section of the terminalpins is less than the diamaeter of the aperture into which the pins arebeing inserted.

The novel apparatus hereof includes feeding means comprising graspingmeans operable only when the feeding means is moving in the firstdirection of travel toward the workpiece to grasp and advance the supplystrip at the juncture of adjacent integrally connected preformedterminal pins. On the return upward stroke, the grasping means are freeto slide relative to the supply strip which is at that point heldstationary by an antireverse checking cam which also coacts with thenotched regions in the supply strip formed by the integrally connectedpreformed terminal pins.

In accordance with a feature of the invention, the feeding means isadjustable relative to the shearing means so that the lengththerebetween can be varied to accept preformed terminal pins of varyinglengths.

In accordance with a further feature of the instant invention, a tandumarrangement may be employed in which the duplicate feeding means eachmay be adjusted independently relative to their respective shearingmeans such that the same apparatus will be capable of multiple injectionof terminal pins of different lengths.

As a further feature of the invention, the shearing means is operable,during shearing of the leading one of the terminal pins, to displace thesevered leading pin to a position under the driving means wherebypositive driving action is assured. Furthermore, during such drivingaction, the severed pin is maintained in its desired position by aspring-biased keeper arrangement.

Accordingly, it is an object of the instant invention to provideapparatus and a supply strip therefor which will insert terminal pinsinto a workpiece such as a printed circuitboard in such a manner as toleave pointed exposed portions of the terminal pins available forelectrical connection thereto.

Another object of the instant invention is to provide such an apparatusand supply strip which is capable of producing and inserting terminalpins of varyi lengths.

Yet another object of the instant invention is to provide such anapparatus and supply strips therefor which is capable of simultaneouslyinserting a plurality of terminal pins and even a plurality of suchterminal pins of differing lengths.

Still another object of the instant invention is to provide such anapparatus and supply strip for inserting pointed terminal pins which mayemploy either circular, rectangular or square configuration.

Still another object of the instant invention is to provide such anapparatus and supply strip which eliminates the burring problem inherentin prior art machines for inserting terminal pins in printedcircuitboards.

These and other objects of the instant invention will be furtherunderstood by referring to the specification and the following drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a side elevational view of the machine of the instantinvention which also illustrates the novel supply strip of the instantinvention.

FIG. 2 is an enlarged front elevation of a portion of the machine of theinstant invention and illustrating the manner in which the feedingmechanism thereof coacts with the novel supply strip of the instantinvention.

FIG. 3 is a view similar to FIG. 2 but illustrating the operation of themachine at a different portion in its cycle of operation.

FIG. 4 is a side view, in section, of the portion of the apparatus shownin FIG. 3.

FIG. 5 is a front elevation of a portion of an alternative embodiment ofthe apparatus of the instant invention in which tandem operation isdisclosed as well as an embodiment in which terminal pins of differinglengths are inserted in a printed circuitboard by the same apparatus.

FIG. 6 is a top view of one embodiment of a terminal pin constructed inaccordance with the teachings of the instant invention.

FIG. 7 is a top view of an alternative embodiment of a terminal pinconstructed in accordance with the teachings of the instant invention.

FIG. 8 is a cross-sectional view taken along the center of a terminalpin constructed in accordance with yet a further embodiment of theinstant invention.

DETAILED DESCRIPTION

Turning to the drawings, wherein like numerals are used to designatelike elements, the machine 10 of the instant invention is seen toinclude a frame generally indicated 12 within which is located motor 14.The output shaft 16 carries pulley 18, the rotation of which iscommunicated by V-belt 20 to main shaft 22 through the intermediate andselective operation of a conventional solenoid actuated, singlerevolution clutch, broadly designated 24. Main shaft 22 is journalledfor rotation in bearings 25 and 26 carried on the main frame 12. At theleftmost end of shaft 22 there is carried a crank 28 having anupstanding pin 30 thereon. A link 32 is connected between pin 30 and apin 34 carried on the rear of a longitudinally reciprocating slidemember 36. Secured to the slide member 36 and movable therewith is ablock 38 which carries the feed mechanism broadly designated 40, theshearing mechanism broadly designated 42, and the driving mechanismbroadly designated 44, the details of all of which will be presented ingreater detail.

Keyed for rotation with main shaft 22 is an eccentric cam 46, the camsurface of which controls the downward stroke of a follower 48, thelower end 50 of which projects through the frame 12 and is engaged withthe rightmost end 52 of a bell crank lever 54 pivoted to the frame at56. The belt crank lever 54 is normally biased counterclockwise aroundits pivot point 56. However, when the follower 48 is depressed by theeccentric cam 46, the bell crank lever 54 rotates clockwise to drive thecutter actuator plunger 58 to the left as viewed in FIG. 1, to actuatethe shearing plunger 60 to sever the leading terminal pin LP (see FIG.4) from the remaining supply strip SS (FIG. 4) of terminal pins. Acompression spring 62 normally maintains the shearing plunger 60 in itsrightmost, non-shearing position.

As can be seen in the Figures, the supply strip SS is in the form of acontinuous length of electrically conductive material formed ofintegrally connected preformed terminal pins 64, the supply strip beingstored in coil form, shown at 65 in FIG. 1, and sequentially advanced bythe reciprocating feeding means 40 in a manner as described with respectto FIGS. 2-4. As seen in the Figures, each of the integrally connectedterminal pins 64 terminate in pointed end portions 66; integrallyconnected adjacent pointed end portions 66 of adjacent pins 64 formingnotched regions in the supply strip SS.

In one embodiment of the instant invention, the terminal pins 64 are ofrectangular or square cross-section such that the pointed end portionsare of prismatic configuration, as illustrated in FIG. 6. In theembodiment wherein the cross-section of the terminal pins is square orrectangular, the maximum dimension illustrated at 68 in FIG. 6, isgreater than the diameter of the aperture 70 (FIG. 2) in the workpiece72 into which the pins 64 are to be inserted whereby a tight-press fitcan be obtained.

In an alternative embodiment of the instant invention, the supply stripis formed of integrally connected preformed terminal pins of circularcross-section such that the pointed end portions are of frustoconicalconfiguration, as illustrated in FIG. 7. In this embodiment, thediameter of the terminal pins, indicated as 74 in FIG. 7, is less thanthe diameter of the aperture 70 in the workpiece 72 into which the pinis to be inserted. Therefore, with this embodiment a region along thelength of each of the terminal pins is enlarged, as illustrated at 76 inFIG. 8, whereby the enlarged region will have a dimension 78 larger thanthe diameter of the aperture 70 in the workpiece 72 into which the pinwill be inserted.

In the preferred method of manufacture of the supply strip of thepresent invention a continuous ribbon of electrically conductivematerial (of rectangular, square, or circular cross-section) is passedthrough notching dies of appropriate configuration which intermittentlyoperate to notch the stock material so as to form the pointed endportions on adjacent terminal pins integrally connected to one another.In the case of stock material of circular configuration, an additionalswaging step is performed on each terminal pin to form the enlargedregion, illustrated at 76 in FIG. 8.

Turning to FIG. 2, it will be seen that the feeding means 40 includesgrasping means in the form of a pivoting feed finger 80 pivoted forrotation about a pivot pin 82 carried by a guide block 84. Guide block84 is slotted, as at 86, and connected to block 38 by screw 88 whereuponby loosening screw 88 the position of guide block 84, and hence theposition of feed finger 80, may be varied along the length of block 38.

Feed finger 80 is normally biased by a small compression spring 90 torotate in a clockwise direction around its axis 82. The end 92 of feedfinger 80 is so configured as to enter the notched regions 94 formedbetween adjacent pointed end portions 66 of adjacent terminal pins 64.Thus when slide member 36 and block 38 are reciprocated in a downwarddirection, as viewed in FIG. 1 and FIG. 2, the end portion 92 of feedfinger 80 (being biased into the notched region 94) causes the supplystrip SS to be advanced toward the workpiece 72. On the return upwardstroke, the feed finger 80 slides freely along the now stationary supplystrip SS held in a stationary position by an anti-reverse motion cammingmeans, broadly designated 96 in FIG. 2.

Anti-reverse motion camming means 96 includes a check-finger 98 mountedfor pivotal rotation on pivot pin 100, carried by another guide block102 fixed to the front face 104 of the frame 12. The second guide block102 likewise includes an elongated slot 106 through which a screw 108passes in securing the guide block 102 to the front face 104. Thus byloosening screw 108, the guide block 102 and hence the check-finger 98may be adjusted along the length of the face 104. Check-finger 98 isbiased in a clockwise direction by a small compression spring 110 housedin the guide block 102. The pointed end 112 of check-finger 98 engagesthe notched regions 94 to prevent the supply strip from moving upwardlyback toward the supply coil 65 when the block 38 and the feed finger 80are reciprocating in their upward path of travel.

The timing of the machine, prearranged by the eccentric cam 46, is suchthat when the downwardly travelling feeding finger 80 has advanced thesupply strip the length of one terminal pin 64, the cutter plunger 60will be actuated toward the left, as viewed in FIG. 4 (by the previouslydescribed action of the bell crank lever 54) to cause the shearing edge114 to sever the leading pin LP from the remaining supply strip SS.During the shearing operation the leading pin LP is displaced laterallyto the left, as viewed in FIG. 4, so as to be placed under the drivingshoulder 116 which then continues to drive the pin into the workpiece72. During the remainder of the downward travel, the leading pin LP ismaintained in its proper position under the driving shoulder 116 by aspring-biased keeper plunger designated 118 carried in the block 38beneath the cutting plunger 60.

As will be appreciated from the above description, certain spatialrelationships must be maintained between the various described elements.For example, the distance between the end 92 of the feeding finger 80and the shearing edge 114 must be either the exact length of one of theterminal pins 64 or a multiple thereof. Only in this manner will it beassured that the shearing edge severs the leading pin LP from the supplystrip SS at the juncture of the integrally connected pointed endportions 66 of adjacent pins 64 forming the notched regions 94 in thesupply strip. This is extremely critical since it guarantees that theend portion of the finally inserted pin will indeed have the pointed endportion which is highly desirable in situations where a wire wrapapplication is to be applied. Likewise, by severing at the mid-point ofthe notched regions 94, the sharpest pointed end portion on the terminalpin is formed thereby eliminating any possibility of an undesirable burrremaining.

It will be appreciated that supply strips formed of integrally connectedpreformed terminal pins of a different length may be employed simply byadjusting the position of guide block 84 to always make sure that thedistance between the driving edge 92 of the feed finger 80 and theshearing edge 114 of the shearing plunger 60 is a multiple of the lengthof the pins 64. Similarly, when the pins 64 are of a different length,the spacing of the guide block 102 will also be changed relative to thespacing of the guide block 84 so that the distance between the end 112of the check-finger 98 and the end 92 of the feed finger 80 will be amultiple of the length of the terminal pins 64.

Turning to FIG. 5, there is illustrated in somewhat schematic form analternative embodiment of the instant invention by which two terminalpins may be simultaneously inserted into a workpiece such as a printedcircuitboard. In such an embodiment, a duplicate set of tooling isemployed, i.e., guide block 102' is also fixed to the front face 102;duplicate feeding means 40' is carried by an enlarged block 38; andduplicate shearing means 42' is likewise carried by guide block 38.Slide member 36 drives block 38 in the manner previously described andan enlarged bar 120 is carried on the face of the cutter actuatorplunger 58 to actuate the shearing plunger 60 and 60' associated witheach of the shearing mechanisms 40 and 42'.

FIG. 5 also illustrates the manner in which the tandem arrangement showntherein may be employed to simultaneously insert terminal pins which areof a different length. For example, it will be seen that the terminalpins 64' are substantially longer than the terminal pins 64 beingprocessed by the tooling shown on the right-hand side of the apparatusof FIG. 5. However, and as described previously, this greater length maybe easily accommodated simply by raising the guide block 84' to makesure that the distance between the end 92' of the feed finger 80'remains either the same length as, or a multiple of, the length of theterminal pins 64'.

While the invention has been described with a certain degree ofparticularity, it will be understood that the description was by way ofexample only and that numerous variations and modifications, as maybecome apparent to those of ordinary skill in the art, can be madewithout departing from the spirit and the scope of the invention ashereinafter claimed.

We claim:
 1. A method for inserting terminal pins into a workpiece; saidmethod comprising:providing a supply strip of integrally connectedpreformed terminal pins connected in longitudinally extending end-to-endrelationship; wherein said preformed terminal pins terminate in pointedend portions, integrally connected adjacent pointed end portions ofadjacent pins forming notched regions in said supply strip; sequentiallyadvancing said supply strip toward said workpiece; shearing the leadingone of said terminal pins from the remainder of said supply strip atsaid notched regions; driving said leading one of said pins into saidworkpiece; and further including the step of holding said leading one ofsaid terminal pins by a holding means after it has been sheared andcontinuing to hold said pin by said holding means while it is beingdriven into said workpiece.
 2. The method of claim 1, wherein the stepof sequentially advancing said supply strip includes: the step ofgrasping said supply strip at said notched regions.